Method of preparing transfer elements



HYDRO PHI uc SOLVENT OLEAGI NOUS IMAGING I BINDER MIXTURE MATERIAL MATERIAL- HARDENING I AGENT l l BINDER PIGMENT SOLUTION I PASTE EMULSIFYING AGENT COATING: COM POSITION APPLIED TO WATER RESISTANT FOUNDATION HEAT A ril 18, 1967 D. A. NEWMAN 3,314,814 v METHOD OF PREPARING TRANSFER ELEMENTS I Filed March 2, 1964 SOLVENT MIXTURE EVAPORATED TO FORM M'ICROPOIZOUS INK-RELEASIHG LAYER,

INVENTOR.

fiouylas 1?, Ne WI770/7 United States Patent 3,314,814 METHOD OF PREPARING TRANSFER ELEMENTS Douglas A. Newman, Glen Cove, N.Y., assignor to Columbia Ribbon and Carbon Manufacturing Co., Inc., Glen Cove, N.Y., a corporation of New York Filed Mar. 2, 1964, Ser. No. 348,822 13 Claims. (Cl. 117-36.1)

This application is a continuation-in-part of earlier copending application Ser. No. 74,790, filed Dec. 9, 1960, now abandoned.

This invention relates to the method of producing inkreleasing transfer elements having a hydrophilic filmforming binder material on a water-resistant foundation.

It is know to prepare transfer elements such as carbon papers and ribbons in which the transfer layer is based upon a film-forming binder material rather than conventional wax binder and is applied to a flexible foundation in the form of a volatile organic solvent solution, rather than by the conventional hot melt method.

It was found that film-formers such as vinyl polymers could be employed to great advantage as carriers or solid bases for pigments in the making of carbon papers and the like, and further that these polymers which are normally cohesive may be changed in their physical characteristics to form an ink-releasing film by compounding them with a non-volatile, non-compatible oily component which is capable of being retained by the polymer, together with coloring matter, and applying them to the foundation sheet as solutions dissolved in one or more volatile organic liquid solvents. The films thus cast are spongy, and while substantially none of the solid vinyl binding agent is transferred to the copy sheet, the noncompatible component and coloring matter exude to the copy sheet under pressure and are absorbed thereby. Thus the image material isessentially fluent and penetrates into the copy paper like a fabric ribbon ink providing a smudge-resistant copy.

While such vinyl resin-based transfer elements enjoy great commercial success and represent a revolutionary advance in the manifolding art, they do present certain problems and disadvantages. Vinyl resins are very cohesive and rubbery so that transfer layers based thereon are subject to changing their dimensions and imaging strength with changes in temperature and humidity. Vinyl resins are relatively expensive and must be applied by means of concentrated volatile organic solvents which are both expensive and dangerous.

It has been proposed to avoid many of these disadvantages by substituting hydrophilic film-forming binder materials for the vinyl resin and substituting water for the volatile organic solvent in the manufacture of transfer elements. However, transfer elements of this type have not met with any degree of commercial success because of the many contradictory requirements such as the necessity of uniformly dispersing the insoluble oily component in the aqueous binder composition and the difficulty of placing the retaining a uniformly thick aqueous layer on a foundation which must be water-resistant.

It is an object of the present invention to attain the beneficial advantages of the vinyl resin-base transfer layers using hydrophilic film-forming binder materials, but in such a way that the above-mentioned disadvantages of both are avoided.

It is another object of this invention is to prepare nonare exceptionally clean to the 3,314,814 Patented Apr. 18, 1967 touch and which which retain these set out hereinafter, will hereinafter appear.

The drawing is a flow sheet illustrating the process of the invention.

In accordance with heretofore presented with the use of hydrophilic binder materials. I have found that it is possible to use oils which are at least partially soluble and preferably completely soluble in the miscible solvent mixture so that a more uniform dispersion of the oil and binder material is possible. I have found that the aliphatic solvent acts as a wetting agent with respect to dispersed oils and also with respect to Water-resistant water alone is used.

The novel transfer composition of this invention comprises a film-forming hydrophilic or water-soluble binder material, a non-volatile oily material which is not combinder materials found suitable are hydromaterials including proteinaceous materials as the vinyl resins and tend to set to a harder, more selfsupporting base material having exceptional dimensional stability.

Other aqueous hydrophilic binder materials such as gelatin,

of the aqueous solvent mixture and separate out as a distinct phase. Such hydrophilic binder materials are excluded from the present invention.

The non-volatile oleaginous material used in the present Preferred for this purpose are the oils such as the mineral, vegetable, animal and synthetic oils, among which may used without separation.

. =3 be listed mineral oil, castor oil, rapeseed oil, sperm oil, olive oil, cottonseed oil, etc. Semi-solid materials such as lanolin, petrolatum and hydrogenated vegetable oil may also be used, particularly in admixture with the abovenamed oils. Other suitable liquid, oily materials include oleic acid, butyl stearate, dibutyland dioctyl-phthalate, tricresyl phosphate and the like. It should be pointed out that the particular non-volatile material must be selected depending upon its non-compatibility with the particular hydrophilic colloid to be used, some of the above-named materials being compatible with some of the above-named colloids. It is preferred that the non-volatile component be highly soluble in the Water-aliphatic solvent mixture of the coating composition. It is somewhat diificult to classify the broad group of non-volatile oleaginous materials useful in the transfer sheets of this invention, other than to say that they are liquid or semi-solid pasty materials which are not compatible with the hydrophilic colloid and cannot be mixed therewith in the proportions Most of the materials found suitable are oils. Others such as butyl stearate, oleic acid, dibutyland dioctyl-phthalate, tricresyl phosphate, lanolin, petrolatum and hydrogenated vegetable oil are oily in nature. Thus, for purposes of the present invention, these materials will hereinafter be referred to as oleaginous materials, such phrase being intended to define the generic group of materials of the type disclosed.

Suitable volatile aliphatic solvents which may be used according to the present invention are those which are compatible with water in aqueous mixtures containing from 3% to 80% by weight of the aliphatic solvent. The preferred aliphatic solvents are the low molecular weight alcohols such as methanol, ethanol, propanol and butanol; low molecular weight esters such as ethyl acetate', low molecular weight ketones such as dimethyland diethyl-ketone and methyl ethyl ketone; and low molecular weight ethers such as Cellosolve.

The aqueous transfer compositions of this invention may be applied to suitable water-resistant or wet strength foundations such as sized or coated papers or plastic films in any desired manner.

In the preferred embodiment, the hydrophilic film-forming material is first dissolved in the solvent mixture. It may be advantageous to employ a hardening agent which serves to insolubilize the hydrophilic material as it sets to form a film on the transfer sheet. This renders the transfer layer even cleaner to the touch and more resistant to changes in humidity or moisture. Suitable insolubilizing agents include glyoxal, ammonium salts, polyvalent metal salts of copper, iron, aluminum, chromium and the like, or any of the other conventional agents well known for this purpose in the art of preparing planographic printing plates.

The dissolved hydrophilic material is then mixed with the pigment paste which has been compounded separately. In many cases it is preferred to do this mixing in the presence of a suitable wetting or emulsifying agent such as Tween (polyoxyalkylene derivative of partial ester of hexitol anhydride and long chain fatty acid), Aerosol AS (diisopropyl naphthalene sodium sulfonate), or the like. Since the volatile aliphatic solvent functions as a wetting agent for the oily material and permits it to be more easily incorporated into the composition, a separate wetting agent may be dispensed with in most instances, particularly in cases where the oily material is soluble to a substantial degree in the water-aliphatic solvent mixture.

The pigment paste comprises suitable coloring matter such as pigment, the oleaginous material and, if desired, an amount of volatile organic solvent such as toluol to facilitate the production of a homogeneously mixed dispersion. The dispersion may also contain small amounts of bodying agents such as lecithin, as well as a combination of pigments and/ or dyes for increased writing strength and color tone.

In preparing the transfer sheets of the present invention, the coating composition is prepared by first mixing the aqueous hydrophilic colloidal solution and the pigment dispersion. The mixture is then spread evenly over a suitable water-resistant foundation by suitable coating apparatus and allowed to dry and harden by evaporation of the volatile solvent mixture to form a smooth pressuresensitive microporous ink-releasing sheet of the type disclosed. It has been found advantageous in some instances to heat the final transfer sheet to help dry and set the transfer layer and provide a cleaner, more smudge-free product.

Depending upon the hydrophilic film-former selected, the pigmentary material or coloring matter used, and the particular oleaginous ingredients employed, there will be substantial variations in the proportions of the ingredients which will produce the optimum results. The best proportions will in each case, however, be readily determinable by anyone skilled in the art of carbon ink preparation. As a guide to suitably selecting the proper proportions, it may be pointed out that in most cases they will lie within the ranges indicated by the following table:

Ingredients: Parts by weight (1) Hydrophilic film-forming material 10 (2) Oleaginous material 15 to 40 (3) Pigment or other coloring matter 3 to 75 (4) Volatile water-aliphatic solvent mixture 1 Amount sufficient to render the mixture readily coatable (usually between about 40 and Illustrative examples of new compositions according to the present invention are as follows:

Example I Ingredients: Parts by weight Zein 7.47 Lanolin 9.70 Mineral oil 7.00 Oleic acid 1.53 Carbon black 4.60 Alkali blue 2.40 Lecithin 1.10 Toluol 3.65 Tween 3.25 Isopropyl alcohol 37.00 Water 22.30

Example 11 Ingredients:

Carboxymethyl cellulose (low viscosity) 6.86 Glyoxal (30% aqueous) 3.00 Lanolin 9.00 Mineral oil 6.60 Carbon black 4.35 Alkali blue 2.25 Oleic acid 3.44 Tween 3.50 Water 31.00 Methyl alcohol 30.00

Example 111 Ingredients:

Polyvinyl alcohol (Elvanol 71-24) 6.80 Glyoxal (30% aqueous) 3.40 Lanolin 9.00 Rapeseed oil 6.60 Carbon black 4.40 Alkali blue 2.20 Lecithin 0.12 Toluol 3.44 Tween 3.50 Water 24.00 Ethanol 36.54

Example IV Ingredients: Parts by weight Zein 4.0 Starch (Dry-Flo) 3.5 Oleic acid 6.6 Lanolin 9.0 Carbon black 2.2 Nigrosine 4.4 Methyl ethyl ketone 3.2 Tween 3.5 Isopropanol 35.4 Water 28.2

The hydrophilic polymer solution and the pigment dispersion containing the oleaginous material and coloring matter are ground together, e.g. in a warm ball mill, until a smooth, uniform consistency is reached. Other colors may be added as desired, either dry or in oil suspension, to intensify the color or change the hue.

The alkali blue, carbon black, nigrosine or other pigments are preferably first dispersed in at least an equal weight of the mineral oil or other non-volatile, noncompatible oleaginous material together with an organic solvent such as toluol to form the pigment dispersion and to simplify their addition to the mixture, this oleaginous material of course being included in computing the total amount permissible in the mixture as above indicated.

The solution of the hydrophilic material is added to the pigment dispersion in an amount suificient to give a water-resistant foundation sheet or web by suitable coating apparatus and allowed to set and harden by evaporation of the volatile solvent mixture to form .a smooth pressure-sensitive carbon coating having the properties described in detail heretofore.

As presently understood, the oleaginous ingredients, which are present in an amount in excess of the amount of the hydrophilic binder as shown in the above examples, and which are non-solvents for and non-compatible with the hydrophilic binder, are uniformly distributed throughprimarily, although probably not entirely, in the discon tinuous phase or pores.

According to the present invention, the binder material is a dimensionally stable film-forming hydrophilic material and the solvent is a compatible mixture of Water and aliphatic solvent, the mixture being less-volatile than the organic solvent per se so where water alone is used as the solvent. The high temperatures required to completely evaporate water per se are sometimes detrimental to the imaging properties of the transfer layer.

While the aqueous compositions of the present invention require the use of water-resistant foundations such as sized papers or papers impregnated with wet strength which are sharply imaged and numerous.

If desired, the imaging material may comprise substantially colorless colorormers which form colored images coreactive complementary colorformer or catalyst. Such materials include dye components, gallic acid-iron chloride systems and the like, well known to the art of carbonless copy.

Variations and modifications may be made within the scope of the claims and portions of the improvements maybe used without other I claim:

1. The process of preparing a pressure-sensitive transfer element having a water-resistant flexible foundation carrying a uniform water-applied pressure-sensitive microand form a microporous structure containing within the pores thereof a pressure-exudable ink composition containing said oleaginous material and said imaging material.

2. The process of claim 1 in which the hydrophilic binder material is selected from the group consisting of proteins, carbohydrates and polyvinyl alcohol.

3. The process according to claim 1 in which. the oleagicroporous coating containing pressure-exudable ink commixture comprisweight of an aliphatic film-forming porous structure containing within the pores thereof a pressure-exudable ink composition containing said oleaginous material and said imaging material.

6. The process according to claim 5 in which the oleaginous material comprises a mixture of an oil and a semisolid pasty material.

7. The process according to claim 5 in which the solvent mixture comprises a major percent by Weight of an aliphatic alcohol and a minor percent by weight of water.

8. The process of preparing a pressure-sensitive transfer element having a water-resistant flexible foundation carrying a uniform water-applied pressure-sensitive microporous coating containing pressure-exudable ink composition, which comprises the steps of forming a coating composition from an azeotropic mixture of Water and from 3% to 80% of an aliphatic solvent, a hydrophilic film-forming binder material which is soluble in said azeotropic mixture, an amount in excess of the amount of binder material of an oleaginous material which is incompatible With said binder tially soluble in said solvent mixture, and a quantity of imaging material; applying said coating composition to a water-resistant flexible foundation selected from the group consisting of sized paper, wet-strength coated paper and plastic film in the form of a coating of uniform thickness, the aliphatic solvent providing the composition with an affinity for the foundation; and evaporating said azeotropic mixture to solidify the coating and form a microporous structure containing within the pores thereof a pressure-exudable ink composition containing said oleaginous material and said imaging material.

9. The process of claim 8 in which the azeotropic solvent mixture comprises water and a low molecular weight aliphatic alcohol.

material and is at least parbinder solution and the pigment paste.

10. The process according to claim 1 in which a hardening agent is included in the coating composition to insolubilize the binder material during solidification of the coating.

11. The process according to claim 1 in which heat is applied to hasten evaporation of the solvent mixture.

12. The process according to claim 1 in which the binder material is first dissolved in the solvent mixture and the oleaginous material is mixed with the imaging material to form a pigment paste and the binder material solution and pigment paste are thereafter mixed to form the coating composition.

13. The process according to claim 12 in which an emulsifying agent is added to assist the mixing of the References Cited by the Examiner MURRAY KATZ, Primary Examiner. 

1. THE PROCESS OF PREPARING A PRESSURE-SENSITIVE TRANSFER ELEMENT HAVING A WATER-RESISTANT FLEXIBLE FOUNDATION CARRYING A UNIFORM WATER-APPLIED PRESSURE-SENSITIVE MICROPOROUS COATING CONTAINING PRESSURE-EXUDABLE INK COMPOSITION, WHICH COMPRISES THE STEPS OF FORMING A COATING COMPOSITION FROM A COMPATIBLE SOLVENT MIXTURE COMPRISING WATER AND FROM 3% TO 80% BY WEIGHT OF AN ALIPHATIC SOLVENT, A HYDROPHILIC FILM-FORMING BINDER MATERIAL WHICH IS SOLUBLE IN SAID SOLVENT MIXTURE, AN AMOUNT IN EXCESS OF THE AMOUNT OF BINDER MATERIAL OF AN OLEAGINOUS MATERIAL WHICH IS INCOMPATIBLE WITH SAID BINDER MATERIAL AND IS AT LEAST PARTIALLY SOLUBLE IN SAID SOLVENT MIXTURE, AND A QUANTITY OF IMAGING MATERIAL; APPLYING SAID COATING COM- 